1. Technical Field of the Invention
This invention relates to telecommunication systems. More particularly, and not by way of limitation, the present invention is directed to a system and method of determining tariffs for wireless calls made to or from ported directory numbers.
2. Description of Related Art
Today, each wireless network operator has its own number series of Mobile Station Integrated Services Digital Network (MSISDN) numbers, referred to herein as directory numbers (DNs). A particular operator can easily tell which subscribers are its own subscribers, and which subscribers belong to other operators, by simply determining whether each subscriber's DN falls within the particular operator's number series. Because the wireless operators can tell which subscribers are their own, the operators typically set up different tariffs for calls between two or more of their own mobile subscribers, between one of their own mobile subscribers and a landline subscriber, or between one of their own subscribers and a mobile subscriber belonging to another wireless operator. For example, one tariff level (T1) may apply to in-network mobile-to-mobile calls between mobile subscribers who subscribe to a particular operator's services. A second tariff level (T2) may apply to calls that are from a landline subscriber to a mobile subscriber who subscribes to the particular operator's services and is operating within the operator's own network. A third level (T3) may apply to inter-network calls from a mobile subscriber in another operator's network towards a mobile subscriber who subscribes to the particular operator's services and is operating within the operator's own network. The operators have rating tables set up for calling numbers and called numbers so they can determine which tariff to set up.
When a call is set up as a prepaid call, or some other service requiring real-time billing, the operator uses the tariff derived from the rating table and deducts money from a prepaid account in real time as the call progresses. If the prepaid account is depleted while the call is still in progress, the operator may terminate the call. For other calls which are not billed in real time (i.e., post-paid calls), call data records (CDRs) are generated after the call is completed, and are sent to a billing center for processing.
Local Number Portability (LNP) (i.e., service provider portability) allows mobile subscribers to retain their directory numbers as the subscribers “port” from one service provider to another. In other words, a subscriber who initially obtains his service from Operator-A, and is provided with a DN within Operator-A's number series, may subsequently change his service to another operator such as Operator-B, and still retain the original DN. Since this subscriber continues to operate with a DN in Operator-A's number series, Operator-B cannot utilize the calling DN or called DN to determine the applicable tariff when the subscriber makes a real-time call such as a prepaid call. For example, if the subscriber above, who is ported-in to Operator-B's network, calls another mobile subscriber who subscribes to Operator-B's services and is operating within Operator-B's own network, the call should be charged at the T1 rate. However, by using the existing rating table, Operator-B would charge the call at the T3 rate because the ported subscriber would appear to be from Operator-A's network.
For post-paid calls, an LNP database is queried prior to the generation of the CDRs to determine whether the calling DN or called DN involved in a call have been ported. When one of the numbers has been ported, the CDRs indicate that fact, and the operators are then able to use their existing rating tables to determine the proper tariff, and to apply the tariff in the post processing. However, for calls requiring real-time billing, the rating using the current methodology will not be correct because the rating of the prepaid call takes place before the LNP database is queried.
In order to overcome this problem, it would be advantageous to have a system and method of determining in real time during call setup, when ported numbers are involved in a call. The present invention provides such a system and method.